Oven-thermo meter



(No Model.) Y i M, T. GREENLEAF. OVEN THE'RMOMETER,

No. 441,299. Patented Nov. 25; 1890;

UNITED- STATES PATENT OFFIcE.

MILLER T. GREENLEAF, OF QUINCY, ILLINOIS.

OVEN-THERMOMETER.

SPECIFICATION forming part of Letters Patent No. 441,299, dated November 25, 1890.

Application filed March 14, 1890. Serial No. 343,887. (No model.)

possess all the functions and capabilities of a higher-priced and more complicated article.

To this end the invention consists of an indicator-shield adapted to be applied to the exterior of the oven-door, a circular casing adapted to be clamped to the interior thereof and carrying the curved compound bar, an indicator moving within said shield, and connections between the shaft thereof and the free end of the compound bar, together with certain specific details of construction of the parts and of their manner of connection and support, which details eifect a greater simplicity and more perfect working of the device, and certain auxiliaries, all as hereinafter more fully described, and illustrated in the accompanying drawings, in which- Figure 1 is an exterior View of an ovendoor with my device applied thereto; Fig. 2 is an interior view of the same with the cover removed. Fig. 3 is a central vertical section, and Fig. 4is an enlarged perspective view, of the indicator-shaft and its connection with the free end of the compound bar. Fig. 5 is an enlarged sectional view of the devices for fastening the end of the compound bar.

Oven-doors have heretofore been provided with indicators controlled by curved compound bars formed of strips of brass and steel fastened together, so that the expansion and contraction of these two metals, due to the variation of the temperature within the oven, would deflectthe free end of the curved bar andmove the indicator. Bimetallic strips have also been heretofore connected at one end to a suitable base and an indicator controlled by the deflection thereof, due to increments and decrements of heat, the conr plete strip forming almost a circle.

Coming now to the present invention, the letter D designates an oven-door or a door of any other chamber of which it is desired to measure the temperature.

S is a shield, and is approximately in the shape .of a shield, provided with an areshaped slot A, below which suitable graduations G are marked, stamped, or raised upon the face of the shield. The body of the latter is preferably dished at its rear side, so that its peripherybears upon the outer face of the door, whereas all other parts thereof are raised above the door.

The letter O designates a metallic casing, which is preferably of the form shown and has a raised flange 0 around its edge adapted to receive the cover 0. Bolts Bpass through ears I) of this casing and through suitable holes in the door D, whereby the shield and easing are held in proper positions upon the exterior and interior of the door. The casing O is provided with a journal J, in which is mounted a shaft S, and an indicator I has its inner end bent around said shaft and clamped to its body by a screw *6, this indicator turning within the shield S and its point showing through the slot therein, as in Fig. 1.

On the inner side of the casing C, a short distance from the journal J, is formed a lug L, through which passes a fastening-screw F, and opposite this lug is a small rib 1, formed upon the interior of the-flange c, as shown in Fig. 5.

The letter O designates a strip of brass, forming almost a complete circle, and the letter P designates a steel wire, brazed or otherwise secured to the outer face of said strip at about the center of its width and throughout its entire length, the ends of this wire beingbent around the ends of the strip, as shown in 'Fig. 2. One end of this compound bar 0 P is seated behind the lug L, with the edge of the plate 0 supported by the bottom of the casing, while the wire P passes over the rib l and rests against the inner side of the flange c. A small wedge WV is then inserted in the opening between the flange c and the stripO and pressed down upon the upper side of the wire P, after which the screw S is turned and this end of the compound bar is securely fastened against all movement or against slipping in any direction.

The free end of the strip 0 below the free end of the wire is extended a trifle, as shown at 0, and provided with a small perforation, and a link K is pivotally engaged at one end in this perforation and is formed into a coil 70 at its other end. The inner end of the shaft S projects through the journal J and is bent over, as shown at s, forming a crank-arm, which passes loosely through said coil, and by this means the free end of the compound bar 1 is connected with the shaft, so that an expanhigher or lower temperature in the oven will be indicated at the exterior of the door=D. By the proper adjustment of the fixed end of the compound bar an operator can cause the tip of the indicator to move from 0 to 6, according as the oven is cold, as when there is no fire in the stove, or is so hot that it will burn anything put into it.

Noting the position of the indicator when the oven is' at proper temperatures for baking bread, short biscuit, cake, and corn-bread, as well as for roasting meats, or for merely warming dishes, the operator can regulate the stove accordingly, and the necessity for opening the oven-door, which so often spoils an otherwise light and delicious cake, is avoided.

What I claim is 1. The combination, with an indicator and a bimetallic bar for moving, said indicator at one end around its other end, of a shield secured to the outer face of the wall of the chamber whose temperature is being indicated, said shield having a semicircular slot over the path of the tip of the indicator, and a scale on its outer face below said slot, the periphery of said shield extending rearwardly through said outer wall, substantially as described. 2. A bimetallic strip composed of a brass strip 0, bent nearly into a ring, and a steel wire P, secured to the outer face thereof, and its ends 19 bent over the ends of the strip, substantially as described.

The casing 0, having the annular flange c, said casing having the apertured lug L, and journal J, in combination with the indicatorshaft mounted in said journal, a bimetallic strip connected at its free endto the crank of said shaft, its other end passing between said lug and the flange of the casing, and a fastening-screw passing through the aperture in said lug, substantially as described.

4. The casing 0, having the apertured lug L, and the flange 0, having a rib Zopposite said lug, in combination with the strip 0, and the rod P secured thereto, one end of these pieces being seated between said lug and rib, the wedge W, between the strip and flange above the rod, and the fastening-screw F, passing through the aperture in said lug, substantially as described.

5. The shaft S and the bimetallic bar connected thereto so as to oscillate it, in combination with the indicator 1, having its inner end bent around said shaft, and the screw 6, passing through said end and the body of the indicator, substantially as described.

6. The casing C, having the journal J, the bimetallic bar of approximately circular shape clamped at one end within said casing and its other end having an aperture 0, in combination with the indicator-shaft S, having a cranked inner end 3, and a link K, pivotally engaged at one end with said perforation, and having a coil at its other end loosely embracing the crank of said shaft, substantially as described.

7. The casing 0, having the annular flange c, said casing having the apertured lug L, and journal J, and a removable cover 0 on said flange, in combination with the indicatorshaft mounted in said journal, a bimetallic strip connected at its free end to the crank of said shaft, its other end passing between said lug and the flange of the casing, and a fastening-screw passing through the aperture in said lug, substantially as described.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in presence of two Witnesses.

MILLER T. GREENLEAF.

Witnesses:

SAMUEL WooDs, W. G. BRoPHY. 

